1. Field of the Invention
This invention relates to a system for detecting missing vehicles, more particularly a system which can detect a missing vehicle on the basis of a signal which is transmitted from a car audio which is installed within the missing vehicle.
2. Prior Art
Various apparatuses for detecting missing vehicles have been suggested in the prior art.
One example of an apparatus for detecting missing vehicles is disclosed in U.S. Pat. No. 5,418,537 to David G. Bird. The apparatus described in the David G. Bird patent uses the Global Positioning System(hereinafter, referred to as GPS) for detecting the present position of a missing vehicle. GPS receives GPS signals which are transmitted from two or more GPS satellites. The apparatus includes a paging responder which responds to a paging signal transmitted from a vehicle location service center. The paging responder causes a controller/modem to interrogate a GPS receiver/processor to determine the present location of the vehicle. The controller/modem then causes a cellular telephone to notify the vehicle location service center of the present location of the missing vehicle, so that the vehicle can be recovered.
However, it is expensive to use the GPS receiver for receiving the GPS signals and the processor for determining the present location of the missing vehicle with the GPS signals. Further, a prerequisite exists that the vehicle to be installed with the apparatus must first be equipped with the mobile telephone.